1. Field of the Invention
The present invention relates to an AC voltage detection circuit and method suitable for raising a charging efficiency, a charging circuit and method having a high charging efficiency, a chopper charging circuit and method, an electronic apparatus, and a timepiece.
2. Description of the Related Art
As a charging circuit for charging a capacitor or a battery with the AC voltage generated by a generator, a bridge type charging circuit has been known. FIG. 51 is a circuit diagram of a conventional charging circuit (Japanese Unexamined Patent Publication (Kokai) No. 9-131064). In this charging circuit, provision is made of comparators COM 1 and COM2 for comparing voltages of output terminals AG1 and AG2 of a generator AG with a power supply voltage Vdd, comparators COM3 and COM4 for comparing the voltages of the output terminals AG1 and AG2 of the generator AG with the voltage of a ground GND, and a capacitor C having a large capacity for storing a charging current. P- and N-channel FETs P1, P2, N1, and N2 are controlled ON and OFF by output of the comparators COM1 to COM4.
Here, when the voltage of the output terminal AG1 becomes the voltage of the ground GND or less, the N-channel FET N1 is brought to the ON state by the comparator COM3, so the output terminal AG1 is grounded. Further, when the voltage of the output terminal AG2 exceeds the power supply voltage Vdd, the P-channel FET P2 is turned ON by the comparator COM2, so a charge is stored in the capacitor C through a route indicated by the arrow. In this case, so far as the voltage of the output terminal AG2 does not exceed the power supply voltage Vdd, the P-channel FET P2 does not turn ON, so a current flows through a route reverse to that indicated by the arrow, to thereby prevent an inconvenience such as a reduction of the charging efficiency.
In this way, in the charging circuit of the related art for charging AC voltage, field effect transistors and comparators are combined to construct a one-directional unit for sending current in one direction under certain conditions and thereby raise the charging efficiency.
In this charging circuit, even in the period when the generator AG does not generate electricity, electrical energy stored in the capacitor C is consumed by the comparators, so there is the problem of a reduction of the charging efficiency.
Further, as a charging circuit charging even when the induced voltage generated in the generator is small, there is a chopper charging circuit. FIG. 52 is a circuit diagram of a chopper charging circuit of the related art (Japanese Unexamined Patent Publication (Kokai) No. 10-282264).
This chopper charging circuit A is provided with comparators COM1 and COM2 for comparing the voltages of the output terminals AG1 and AG2 of the generator AG with the power supply voltage Vdd, P-channel FETs P1, P2 controlled ON and OFF by output signals SP1 and SP2 of the comparators COM1 and COM2, an oscillator circuit B for outputting a clock signal CL, an AND circuit AND for calculating an AND logic of the output signals SP1 and SP2 of the comparators COM1 and COM2 and the clock signal CL, N-channel FETs N1, N2 controlled by an output signal SN of the AND circuit AND, and a capacitor C having a large capacity for storing the charging current. Here, diodes d1, d2, d3, and d4 are parasitic diodes of the P- and N-channel FETs P1, P2, N1, and N2 respectively.
Next, an explanation will be made of an operation of this chopper charging circuit A by using a timing chart shown in FIG. 53. In this example, it is assumed that, up to a time ta, the voltages of the output terminals AG1 and AG2 are the power supply voltage vdd or less, the output signals SP1 and SP2 of the comparators COM1 and COM2 are maintained at the high level, and the P-channel FETs P1 and P2 are in the OFF state.
First, in this chopper charging circuit A, when the clock signal CL becomes the high level at the time ta, the output signal SN of the AND circuit AND becomes the high level, so the N-channel FETs N1 and N2 become the ON state, and a short-circuit route of the AC generator AG and N-channel FETs N1 and N2 is formed. In this case, when induced voltage is generated on for example the output terminal AG1 side in accordance with the induced voltage of the AC generator AG, as indicated by a symbol a in FIG. 52, a current i1 flows through the route from the AC generator AG via N-channel FET N1 to N-channel FET N2.
Then, when the clock signal CL becomes the low level at a time tb, the output signal SN of the AND circuit AND becomes the low level, so the N-channel FETs N1 and N2 become the OFF state, and the short-circuit route is cut. In this case, while the clock signal CL is at the high level (hereinafter, referred to as a xe2x80x9cshort-circuit periodxe2x80x9d), energy is stored in an inductance of an output coil of the AC generator AG by the current flowing through the short-circuit route, and the voltage of the output terminal AG1 is boosted by this energy. Then, when the voltage of the output terminal AG1 is boosted to the power supply voltage Vdd or more at a time tc, the output signal SP1 of the comparator COM1 turns tothe low level, and the P-channel FET P1 turns to the ON state. Consequently, as indicated by a symbol xcex2 in FIG. 52, a charging current i2 flows through a charging route from the diode d4 via AC generator AG and P-channel FET P1 to capacitor C, so that the capacitor C is charged.
In this case, along with progress in the charging, the energy stored in the inductance of the output coil is gradually discharged, and the charging current i2 is gradually reduced. Then, when the voltage of the output terminal AG1 becomes the power supply voltage Vdd or less, the output signal SP1 of the comparator COM1 becomes the high level, the P-channel FET P1 switches to the OFF state, and the charging route mentioned above is cut. Namely, until the voltage of the output terminal AG1 becomes the power supply voltage Vdd or less, the N-channel FETs N1 and N2 are maintained in the OFF state by the AND circuit AND, and the charging is continued.
Accordingly, when the amount of the generated power of the AC generator AG is large and the energy stored in the inductance of the output coil is large, the charging is continued even if shifting to the short-circuit period. Note that when induced voltage is generated on the output terminal AG2 side of the AC generator AG, the direction of the current i1 flowing through the above short-circuit route becomes reverse, and the voltage of the output terminal AG2 is boosted. Consequently, the charging current i2 flows through the charging route from the diode d3 via AC generator AG and P-channel FET P2 to capacitor C, so that the capacitor C is charged.
In this way, the chopper charging circuit of the related art boosts the voltage by converting the induced voltage of the AC generator to the chopper voltage and thereby can charge even when the induced voltage generated in the AC generator is small.
Incidentally, in a comparator configured by a field effect transistors, the lower in transition frequency, the smaller the current consumption. Further, the operating speed of the comparator is determined by the transition frequency of the field effect transistor configuring the comparator, so the smaller the current consumption, the slower the operation of the comparator. For this reason, as mentioned above, when a low current consumption type power generation detection comparator is provided in the charging circuit, the comparator cannot detect the induced voltage even if an induced voltage exceeding a threshold voltage is generated, so detection of power generation is not done quickly.
Here, it may be considered to detect power generation early by lowering the threshold voltage of the power generation detection comparator. However, by lowering the threshold voltage, a malfunction can occur when noise is induced in the output coil of the AC generator AG, so there is a limit to the reduction of the threshold voltage.
A concrete explanation will be made of this point. FIG. 54 shows the relationship between an induced voltage VG generated between the output terminals AG1 and AG2 and the threshold voltage VD. In this example, the threshold voltage VG is set so that no malfunctions occur due to noise N. For this reason, there is the problem such that the state of generation cannot be detected irrespective of the induced voltage being generated during a period from a time t0 to a time t1.
Further, in the chopper charging circuit, when the induced voltage generated between the output terminals AG1 and AG2 is extremely small, the energy stored in the inductance of the output coil is small, so the voltage cannot be boosted to the power supply voltage Vdd or more even if the induced voltage is inverted to the chopper voltage. For this reason, the capacitor C cannot be charged, and the chopper voltage is consumed by an internal resistance or the like of the output coil.
Further, even if the induced voltage generated between the output terminals AG1 and AG2 is large, when the charging is started and the chopper voltage becomes the power supply voltage Vdd or less, the capacitor C cannot be charged.
It may be considered that the charging efficiency of the chopper charging circuit could be further raised if the energy stored in the inductance consumed by the internal resistance etc. of the output coil could be charged in the capacitor C.
An object of the present invention is to provide an AC voltage detection circuit and method capable of raising the charging efficiency and a charging circuit and method, a chopper circuit and chopping method, a chopper charging circuit and method, an electronic apparatus, and a timepiece applying them.
According to an aspect of the present invention, there is provided an AC voltage detection circuit for detecting whether or not an AC voltage having an amplitude not less than a predetermined amplitude was induced in an inductance element connected between a first input terminal and a second input terminal, provided with a first capacity element connected to the first input terminal, a second capacity element connected to the second input terminal, a charging unit for forming a charging route including a capacity element connected to one input terminal between the first and second input terminals and cutting off a charging route including a capacity element connected to the other input terminal when induction of the AC voltage is started at the inductance element, and a detection unit for comparing the voltages of the first input terminal and the second input terminal with a reference voltage and detecting that the AC voltage was induced in the inductance element in accordance with the result of the comparison.
According to another aspect of the present invention, there is provided an AC voltage detection circuit for detecting whether or not an AC voltage having an amplitude not less than a predetermined amplitude was induced in an inductance element connected between a first input terminal and a second input terminal, provided with a first diode connected between the first input terminal and a line, a first capacity element and a first switching element connected between the first input terminal and the line, a second diode connected between the second input terminal and the line, a second capacity element and a second switching element connected between the second input terminal and the line, a control unit for controlling to turn ON one of the first and second switching elements and turn OFF the other in a period when a continuous AC voltage is induced at the inductance element and, at the same time, controlling to turn ON the switching element connected between the input terminal having a lower terminal voltage immediately before the end of the related period between the first and second input terminals and the line after the end of the related period, and a detection unit for comparing the voltages of the first input terminal and the second input terminal with the reference voltage, and detecting that the AC voltage of the amplitude not less than the predetermined amplitude was induced at the inductance element in accordance with the result of the comparison.
Preferably, the AC voltage detection circuit further includes a discharging unit for discharging a charged element between the first or second capacity elements at a point of time when the induction of the AC voltage is detected by the detection unit.
Advantageously, the discharging unit is provided with a third switching element connected between the first input terminal and the line and a fourth switching element connected between the second input terminal and the line and turns ON the third or fourth switching element corresponding to the element which has been turned ON between the first and second switching elements at the point of time when induction of an AC voltage not less than the predetermined amplitude is detected by the detection unit.
According to another aspect of the present invention, there is provided a charging circuit for rectifying an AC voltage induced at an inductance element connected between a first input terminal and a second input terminal and charging a capacity element connected between a first line and a second line, provided with a first switching element connected between the first line and the first input terminal, a second switching element connected between the first line and the second input terminal, a third switching element and a first diode connected in parallel between the second line and the first input terminal, a fourth switching element and a second diode connected in parallel between the second line and the second input terminal, a fifth switching element and a first auxiliary capacity element connected in series between the second line and the first input terminal, a sixth switching element and a second auxiliary capacity element connected in series between the second line and the second input terminal, a first control unit for controlling the ON or OFF state of the first through fourth switching elements based on potentials of the first and second lines and the potentials of the first and second input terminals, a power supply unit for comparing the voltages between the first and second input terminals and the second line with the reference voltage and supplying power to the first control unit when detecting that an AC voltage not less than a predetermined amplitude was induced at the inductance element in accordance with the result of the comparison, and a second control unit for turning ON the fifth or sixth switching element corresponding to the input terminal having the lower terminal voltage immediately before the end of the period where the continuous AC voltage is induced at the inductance element after the end of the related period.
According to still another aspect of the present invention, there is provided a chopper charging circuit for chopper boosting AC voltage induced at an inductance element connected between a first input terminal and a second input terminal synchronous to a clock signal and charging a capacity element connected between a first line and a second line, provided with a first switching element connected between the first line and the first input terminal, a first control unit for comparing the potential of the first line and the potential of the first input terminal and controlling the ON or OFF state of the first switching element based on the result of the comparison, a second switching element connected between the first line and the second input terminal, a second control unit for comparing the potential of the first line and the potential of the second input terminal and controlling the ON or OFF state of the second switching element based on the result of the comparison, a third switching element and a first diode connected in parallel between the second line and the first input terminal, a third control unit for comparing the potential of the second line and the potential of the first input terminal and turning ON or OFF the third switching element synchronous to the clock signal based on the result of the comparison, a fourth switching circuit and a second diode connected in parallel between the second line and the second input terminal, a fourth control unit for comparing the potential of the second line and the potential of the second input terminal and turning ON or OFF the fourth switching element synchronous to the clock signal based on the result of the comparison, a fifth switching circuit and a first auxiliary capacity element connected in series between the second line and the first input terminal, a sixth switching circuit and a second auxiliary capacity element connected in series between the second line and the second input terminal, a detection unit for comparing the voltages between the first and second input terminals and the second line with the reference voltage and detecting that an AC voltage not less than the predetermined amplitude was induced at the inductance element in accordance with the result of the comparison, a power supply unit for supplying power to the first through fourth control units after it is detected by the detection unit that an AC voltage not less than the predetermined amplitude was induced, and an auxiliary capacity element selection unit for turning ON the fifth or sixth switching element corresponding to an input terminal having a lower terminal voltage immediately before the end of the period where the continuous AC voltage is induced at the inductance element after the end of the related period.
Preferably, the discharging unit turns ON or OFF the element which has become ON between the fifth and sixth switching element synchronous to the ON or OFF state of the third or fourth switching element corresponding to the related element at the point of time when it is detected by the detection unit that an AC voltage not less than the predetermined amplitude is induced.
According to yet another aspect of the present invention, an electronic apparatus includes a built-in chopper charging circuit of the above-mentioned type, and operates by power supplied from the chopper charging circuit.
According to another aspect of the present invention, a timepiece is provided with a chopper charging circuit of the above-mentioned type, and a clock circuit for counting and displaying time by power supplied from the chopper charging circuit.
According to another aspect of the present invention, there is provided an AC voltage detection method for detecting whether or not an AC voltage not less than a predetermined amplitude was induced at an inductance element inserted between a first input terminal with a first capacity element connected thereto and a second input terminal with a second capacity element connected thereto, comprising forming a charging route including a capacity element connected to one input terminal between the first and second input terminals, cutting a charging route including the capacity element connected to the other input terminal, comparing the voltages of the first input terminal and the second input terminal with the reference voltage, and detecting that the AC voltage was induced at the inductance element in accordance with the result of the comparison when induction of AC voltage is commenced at the inductance element.
According to another aspect of the present invention, there is provided an AC voltage detection method using a detection circuit provided with a first diode connected between a first input terminal and a line, a first capacity element and a first switching element connected between the first input terminal and the line, a second diode connected between a second input terminal and the line, and a second capacity element and a second switching element connected between the second input terminal and the line so as to detect whether or not an AC voltage not less than a predetermined amplitude was induced at an inductance element connected between the first input terminal and the second input terminal, comprising turning ON one of the first and second switching elements and turning OFF the other in a period where a continuous AC voltage is induced at the inductance element, turning ON the switching element connected between the input terminal having a lower terminal voltage immediately before the end of the related period between the first and second input terminals and the line after the end of the related period, comparing the voltages of the first input terminal and the second input terminal with the reference voltage, and detecting that an AC voltage not less than the predetermined amplitude was induced at the inductance element in accordance with the result of the comparison.
According to another aspect of the present invention, there is provided a charging method using a charging circuit provided with a first switching element connected between a first line and a first input terminal, a second switching element connected between the first line and a second input terminal, a third switching element and a first diode connected in parallel between the second line and the first input terminal, a fourth switching element and a second diode connected in parallel between the second line and the second input terminal, a fifth switching element and a first auxiliary capacity element connected in series between the second line and the first input terminal, and a sixth switching element and a second auxiliary capacity element connected in series between the second line and the second input terminal so as to rectify the AC voltage induced at the inductance element connected between the first input terminal and the second input terminal and charge a capacity element connected between the first line and the second line, comprising the steps of comparing the voltages between the first and second input terminals and the second line with a reference voltage, detecting that an AC voltage not less than a predetermined amplitude was induced at the inductance element in accordance with the result of the comparison, controlling the ON or OFF states of the first through fourth switching elements based on the potentials of the first and second lines and the potentials of the first and second input terminals, and turning ON the fifth or sixth switching element corresponding to the input terminal having the lower terminal voltage immediately before the end of the period when a continuous AC voltage is induced at the inductance element after the end of the related period.
According to another aspect of the present invention, there is provided a chopper charging method using a chopper charging circuit provided with a first switching element connected between a first line and a first input terminal, a first control unit for comparing the potential of the first line and the potential of the first input terminal and controlling the ON or OFF state of the first switching element based on the result of the comparison, a second switching element connected between the first line and the second input terminal, a second control unit for comparing the potential of the first line and the potential of the second input terminal and controlling the ON or OFF state of the second switching element based on the result of the comparison, a third switching element and a first diode connected in parallel between the second line and the first input terminal, a third control unit for comparing the potential of the second line and the potential of the first input terminal and turning ON or OFF the third switching element synchronous to the clock signal based on the result of the comparison, a fourth switching circuit and a second diode connected in parallel between the second line and the second input terminal, a fourth control unit for comparing the potential of the second line and the potential of the second input terminal and turning ON or OFF the fourth switching element synchronous to the clock signal based on the result of the comparison, a fifth switching circuit and a first auxiliary capacity element connected in series between the second line and the first input terminal, and a sixth switching circuit and a second auxiliary capacity element connected in series between the second line and the second input terminal, comprising the steps of comparing the voltages between the first and second input terminals and the second line with the reference voltage, detecting that an AC voltage not less than a predetermined amplitude was induced at the inductance element in accordance with the result of the comparison, supplying power to the first through fourth control units after it is detected by the detection unit that an AC voltage not less than the predetermined amplitude was induced, and turning ON the fifth or sixth switching element corresponding to the input terminal having the lower terminal voltage immediately before the end of the period where the continuous AC voltage is induced at the inductance element after the end of the related period.
According to another aspect of the present invention, there is provided a chopper circuit for converting energy supplied from a power supply to a chopper voltage to generate a chopper voltage between a first line and a second line, provided with an inductance element, a storage unit for storing the power, a first chopper unit for forming a first closed loop including the inductance element and the power supply to supply the power of the power supply to the inductance element and converting the energy of the inductance element to the chopper voltage by opening the first closed loop after an elapse of a predetermined period, a charging unit for charging the storage unit by forming a second closed loop including the inductance element and the storage unit where the chopper voltage converted by the first chopper unit becomes a chopper reference voltage determined in advance or less, and a second chopper unit for forming a third closed loop including the inductance element and the storage unit and converting the energy of the inductance element to the chopper voltage by opening the third closed loop after the elapse of the predetermined period.
According to a still another aspect of the present invention, there is provided a chopper circuit for converting a energy supplied from an AC power supply to a chopper voltage to generate a chopper voltage between the first line and the second line, provided with an inductance element, first and second storage units for storing the power, a first chopper unit for forming a first closed loop including the inductance element and the AC power supply to supply power of the AC power supply to the inductance element and opening the first closed loop after the elapse of a predetermined period to thereby to convert the energy of the inductance element to the chopper voltage, a first charging unit for forming a second closed loop including the inductance element and the first storage unit to charge the first storage unit by the chopper voltage when the chopper voltage converted by the first chopper unit and generated on one terminal side of the inductance element becomes a chopper reference voltage determined in advance or less, a second charging unit for forming a third closed loop including the inductance element and the second storage unit to charge the second storage unit by the chopper voltage when the chopper voltage converted by the first chopper unit and generated on the other terminal side of the inductance element becomes the chopper reference voltage or less, a second chopper unit for forming a fourth closed loop including the inductance element and the first storage unit and opening the fourth closed loop after the elapse of the predetermined period to thereby convert the energy of the inductance element to the chopper voltage, and a third chopper unit for forming a fifth closed loop including the inductance element and the second storage unit and opening the fifth closed loop after the elapse of the predetermined period to thereby convert the energy of the inductance element to the chopper voltage.
According to another aspect of the present invention, there is provided a chopper method providing an inductance element and a storage unit for storing power and converting voltage supplied from a power supply to a chopper voltage to generate a chopper voltage between a first line and a second line, comprising a first chopper step of forming a first closed loop including the inductance element and the power supply to supply power of the power supply to the inductance element and opening the first closed loop after the elapse of a predetermined period to thereby convert the energy of the inductance element to the chopper voltage, a charging step of forming a second closed loop including the inductance element and the storage unit to charge the storage unit by the chopper voltage when the chopper voltage converted by the first chopper step becomes a predetermined chopper reference voltage or less, and a second chopper step of forming a third closed loop including the inductance element and the storage unit and opening the third closed loop after the elapse of a predetermined period to thereby convert the energy of the inductance element to the chopper voltage.
According to another aspect of the present invention, there is provided a chopper method providing an inductance element and first and second storage units for storing power and converting a voltage supplied from an AC power supply to a chopper voltage to generate a chopper voltage between a first line and a second line, comprising a first chopper step of forming a first closed loop including the inductance element and the AC power supply to supply power of the AC power supply to the inductance element and opening the first closed loop after the elapse of the predetermined period to thereby convert the energy of the inductance element to the chopper voltage, a first charging step of forming a second closed loop including the inductance element and the first storage unit to charge the first storage unit by the chopper voltage when the chopper voltage converted by the first chopper step and generated on one terminal side of the inductance element becomes a predetermined chopper reference voltage or less, a second charging step of forming a third closed loop including the inductance element and the second storage unit to charge the second storage unit by the chopper voltage when the chopper voltage converted by the first chopper step and generated on the other terminal side of the inductance element becomes the chopper reference voltage or less, a second chopper step of forming a fourth closed loop including the inductance element and the first storage unit and opening the fourth closed loop after the elapse of the predetermined period to thereby convert the energy of the inductance element to the chopper voltage, and a third chopper step of forming a fifth closed loop including the inductance element and the second storage unit and opening the fifth closed loop after the elapse of the predetermined period to thereby convert the energy of the inductance element to the chopper voltage.
According to yet another aspect of the present invention, there is provided a chopper charging circuit provided with a chopper circuit for converting voltage supplied from a power supply to a chopper voltage to generate a chopper voltage between a first line and a second line and a third storage unit for storing the chopper voltage of the chopper circuit, wherein the chopper circuit is provided with an inductance element, a storage unit for storing power, a first chopper unit for forming a first closed loop including the inductance element and the power supply to supply power of the power supply to the inductance element and opening the first closed loop after the elapse of a predetermined period to thereby convert the energy of the inductance element to the chopper voltage, a charging unit for charging the storage unit by forming a second closed loop including the inductance element and the storage unit when the chopper voltage converted by the first chopper unit becomes a predetermined chopper reference voltage or less, and a second chopper unit for forming a third closed loop including the inductance element and the storage unit and opening the third closed loop after the elapse of the predetermined period to thereby convert the energy of the inductance element to the chopper voltage.